Add class MDFormatter for formatting contents in markdown

MDFormatter.php

@@ -0,0 +1,167 @@
+<?PHP
+/**
+ * Applies plain text formatting.
+ *
+ * @author Joshua Ramon Enslin <joshua@museum-digital.de>
+ */
+declare(strict_types = 1);
+
+/**
+ * Applies plain text formatting.
+ */
+final class MDFormatter {
+
+    /** @var boolean */
+    public static bool $use_underlined_hl = true;
+
+    /**
+     * Applies markdown formatting for main headline.
+     *
+     * @param string $input Headline text.
+     *
+     * @return string
+     */
+    public static function formatMarkdownHeadline1(string $input):string {
+
+        if (self::$use_underlined_hl === false) {
+            return '# ' . $input . PHP_EOL . PHP_EOL;
+        }
+
+        $hlLength = mb_strlen($input);
+
+        $output = $input . PHP_EOL;
+        for ($i = 0; $i < $hlLength; $i++) {
+            $output .= '=';
+        }
+        $output .= PHP_EOL . PHP_EOL;
+
+        return $output;
+
+    }
+
+    /**
+     * Applies markdown formatting for secondary headline.
+     *
+     * @param string $input Headline text.
+     *
+     * @return string
+     */
+    public static function formatMarkdownHeadline2(string $input):string {
+
+        if (self::$use_underlined_hl === false) {
+            return '## ' . $input . PHP_EOL . PHP_EOL;
+        }
+
+        $hlLength = mb_strlen($input);
+
+        $output = $input . PHP_EOL;
+        for ($i = 0; $i < $hlLength; $i++) {
+            $output .= '-';
+        }
+        $output .= PHP_EOL . PHP_EOL;
+
+        return $output;
+
+    }
+
+    /**
+     * Applies markdown formatting for tertiary headline.
+     *
+     * @param string $input Headline text.
+     *
+     * @return string
+     */
+    public static function formatMarkdownHeadline3(string $input):string {
+
+        return '### ' . $input . PHP_EOL;
+
+    }
+
+    /**
+     * Returns a horizontal rule in markdown.
+     *
+     * @return string
+     */
+    public static function formatMarkdownHorizontalRule():string {
+
+        return '___' . PHP_EOL;
+
+    }
+
+    /**
+     * Applies markdown formatting for a named link.
+     *
+     * @param string $link_name Link text.
+     * @param string $link_url  Target URL.
+     *
+     * @return string
+     */
+    public static function formatMarkdownNamedLink(string $link_name, string $link_url):string {
+
+        return "[{$link_name}]({$link_url})";
+
+    }
+
+    /**
+     * Applies markdown formatting for a block quote.
+     *
+     * @param string $content Content of the block quote.
+     *
+     * @return string
+     */
+    public static function formatMarkdownBlockQuote(string $content):string {
+
+        $output = '';
+        $lines = \explode(PHP_EOL, $content);
+
+        foreach ($lines as $line) {
+            $output .= '> ' . $line . PHP_EOL;
+        }
+
+        return $output;
+
+    }
+
+    /**
+     * Applies markdown formatting for a code block.
+     *
+     * @param string $content  Content of the code block.
+     * @param string $language Progamming language for syntax highlighting. Optional.
+     *
+     * @return string
+     */
+    public static function formatMarkdownCodeBlock(string $content, string $language = ''):string {
+
+        $output = '```' . $language . '
+' . $content . '
+```' . PHP_EOL;
+
+        return $output;
+
+    }
+
+    /**
+     * Applies markdown formatting for an unordered list item.
+     *
+     * @param string $content Content of the list item.
+     *
+     * @return string
+     */
+    public static function formatMarkdownUnorderedListItem(string $content):string {
+
+        if (\strpos($content, PHP_EOL) === false) {
+            return '- ' . $content . PHP_EOL;
+        }
+
+        $lines = \explode(PHP_EOL, $content);
+        $output = '- ' . $lines[0] . PHP_EOL;
+
+        foreach ($lines as $i => $line) {
+            if ($i === 0) continue;
+            $output .= '  ' . $line . PHP_EOL;
+        }
+
+        return $output;
+
+    }
+}